In manufacture of food powders and liquids, such as dairy powders, dairy liquids, soups and sauces, magnetic metal particles must be removed prior to metal detectors in order to provide metal fragment free final products.
Such materials are conveyed by pneumatic or vacuum lines or in pipelines of liquid pumped under pressure to a location at which the final products is packaged.
A problem with current devices is the difficulty in magnetically extracting magnetic contamination without causing other material flow problems.
A variety of devices are available to remove contaminants from a flowable substance. As a particular example, magnetic devices are employed to remove magnetic material from material passing along a predetermined path through, over or under the magnetic device. Magnets within the device attract the magnetic material and remove it from the material flow. The magnets are then subsequently cleaned.
The above devices are often in the form of fixed bars across a material flow with the consequent that it is difficult to prevent blockage when there is particulate in the product. Further such bars are subject to localised abrasion where product strikes the fixed bars. Impact of product on bars or probes can cause product damage, blockage or adversely affect bulk density of packaged powder products.
Spherical magnets are also used in pipelines handling grain products and powders. These devices require a nose cone to achieve separation efficiency by reducing resistance to flow and product impingement. Where product is abrasive, a replaceable cap is used to protect the portion of the sphere around the nose cone. This may enable localised wear areas to be renewed but provides a crevice trap for contamination and moisture under the replaceable cap which is unacceptable in sensitive, hygienic circumstances.
When bolts have been used to hold down an aerodynamically designed nosing to a sphere or bar, removing and replacing bolts has proved impracticable. A totally welded on device (where possible due to magnetic field) solves the hygiene problem, but where abrasive wear occurs, the whole magnet has to be replaced.